Manufacture of new cellulose derivatives



i atented Aug, 7,

entrain @FFEQEO LEON LILIENFELD, @F VIMNHA, AUSTRIA.

UFAC'LURE 0% NEW CELLULUSE DERIIVATIVES.

No Drawing. Application filed may 22, 1926, Serial lilo. 111,035, and inAustria may 30, 19535.

As is known, it has hitherto not been possible to prepare esters ofcellulose-Xanthic acids.

According to the present invention esters of cellulose-xarithic acidsmay be made 'by acting on a cellulose-xanthic acid or a cellulosexanthate with an ester of an inorganic acid under faintly alkaline,neutral or acid conditions.

As parent materials for the invention there come into question thecellulose-Kan t-hic acids and cellulose-xanthates (viscose) obtainableby any known method with any desired practicable proportions of alkalilye and carbon-disulphide. F or the preparation of these parentmaterials there may be used bleached or unbleached cellulose as such inany form in which it is obtainable in commerce, such as cellulosehydrate, hydrocellulose, oxycellulose, or any cellulose derivativescontaining a free hydroxyl group which permits their conversion into athionthiol-carboxylic acid ester.

llhe cellulose-xanthic acid or cellulosexanthate may be caused to' reacteither as such (that is in the form of their compounds with an alkali,but without an ap-- preciable excess of alkali, for example, a crude orpurified viscose which has been rendered neutral or acid by means of aweak acid), or in the form of a compound with another metal, for examplezinc. When the parent material is a crude viscose there may be usedeither the product of the reaction between carbon disulphide andalkali-cellulose, before it is dissolved, or a concentrated or diluteviscose solution, of reaction which is only slightly alkaline, or isneutral or acid. If a purified cellulose-Xanthic acid orcellulose-xanthate is used in the invention, any known method ofpurification may be used. There may be mentioned, for example,precipitation by means of a solution of a salt or by means of alcohol,with or without previous neutralization or acidification by means of aweak acid, followed by washing the precipitated material with a solutionI of a salt or with diluted alcohol; precipitation by meansof carbondioxide and subsequent washing; treatment with sulphui'ous acid or witha bisu-lphite; dialysis, or the like. Wherever the context permits, theexpressions viscose, cellulose-xanthic acid, or *cellulose-Xanthate usedin the description and claims shall include the forms ofcellulose-xanthic acids or cellulose-xanthates (viscose) referred to inthis and the preceding paragraph.

lln cases in which the viscose is at the cornmencement only slightlyalkaline or neutral, so whether this be due to the fact that only asmall excess of alkali has been used in its preparation, or that its haspreviously been purified, it is not absolutely necessary to neutralizethe alkali before acting on it with the ester of an inorganic acid.

Generally, the reaction between the cellulose-xanthic acid or thecellulose-xanthate and the ester of an inorganic acid occurs withoutextraneous supply of heat, but if F0 desired, the reaction may beinitiated or I accelerated by warming.

The formation of the new cellulose compounds is indicated by theprecipitation of the final product, which tends to separate in the form.of a jelly in cases when a, concentrated viscose is used as the parentmaterial, and the mixture is stirred only slightly. If, however, thereaction mixture is more dilute, and is stirred, the new derivativesseparate as a fine or coarse precipitate.

The product may be isolated, for instance, by separating the precipitateor jelly from the liquor by filtering, straining, centrifugas ing or thelike. if the precipitate is a jelly or a bulky precipitate, it isdesirable to comminute it before washing. The washing with water may bepreceded by washing with alcohol, or by washing with alcohol and thenwith ether, benzene or the like. After washing, the product may be usedin the wet state (if desired after removal of the bulk of the adheringwashing liquid by pressing, suction or centrifuging), or itmay e5 rst bedried.

According tothe mode of their formation, and their chemicalcharacteristics, the new compounds are in all probability esters ofcellulose-xanthic acid of the type lllll Hill in the simplest manner bythe following equation, in which the reaction between a sodiumcellulose-xanthate and ethyl iodide has been chosen as an example Asodium cellulose-xauthate.

The new cellulose derivatives obtainable according to the invention areuseful in part in themselves for the production of artificial products,such as artificial threads,

films, plates, bands, plastic masses, coatings and layers of every kind,and in part as parent material for the manufacture-of other compounds orderivatives of cellulose.

The following examples illustrate the, invention, the parts being byweight Example 1.-1000 parts of a crude viscose (prepared for instanceby soaking 100 parts of sulphite-cellulose in sheet or fleece-form in1000-2000 parts of a caustic soda lye of sponding with 100 parts ofparent cellulose,

are diluted, either in the fresh state or after allowing'to stand for ashort or long period (for example, 6 hours to 3 days), with 9000-v 10000parts of water, and are then treated whilst stirring with dilute aceticacid (for example, acetic acid of 5-10 per cent strength), until thereaction is faintly alkaline, or neutral or acid. As soon as thehydrogen-sulphide liberated during the neutralization has escapedcompletely or in greater part, 100 parts of diethyl sulphate are addedto the viscose, which has become lightin colour, and'the mixture isstirred. After about an hour, the mass becomes gelatinous, but soonbecomes liquid again with-.the precipitation of a fine flakyprecipitate. This precipitate is separated from the mother liquor bystraining, centrifuging, filtering, pressing, decanting or the like,either immediatelyafter its formation, or after allowing the mixture tostand for several hours or days. It is then washed with water and driedin a vacuum or in the air, if desired after freeing it from water bymeans of alcohol, and washing with ether. The product is a white powder,particularly after it has been ground.

It is soluble in dilute alkali lye, for instance, in a caustic sodasolution of 8-10 per cent strength, and also in many organic solvents,for instance, in an aqueous solution of pyridine of 70-80 per centstrength.

Ewample2.-1000 parts of a viscose of 10 per cent strength (calculated onthe parent cellulose), prepared as described in xample 1, are dilutedwith 5000-10000parts 4 Ethyl ester of a cellulose-xanthic acid. 1

of water, and treated with a weak acid (for instance, acetic acid of 10per cent strength) until the reaction is very faintly alkaline, orneutral, or acid. To the viscose which has become colourless, there arethen 'addedwhilst stirring, 100-170 parts of ethyliodide, and themixture is vigorously stirred after the addition is completed. Accordingto the extent of dilution of the viscose, the

reaction-mixture thickens and becomes slimy and gelatinous after ashorter or longer period, and then again becomes liquid: the product ofthe reaction meanwhile separating in the form of fine or coarse flakesor grains. It may be isolated in the manner described in the precedingexample.

The ethyl ester of the cellulose-xanthic acid is a white powdery orflaky substance, particularly after comminution; it is soluble in dilutealkali lye, for instance in a caustic soda solution of 10 per centstrength, to a clear viscose solution, usually after swelling for sometime. The solution may be worked up into transparent, shining, flexibleartifi- 01211 products such as films, artificial threads (particularlyartificial silk), plastic masses, coatings and layers of every kind, andthe like, by bringing the solution into a suitable form and coagulatingit by means of a suitable precipitating agent, for example, a diluteacid or a solutlon of a, salt, in short, any precipitating agent knownin the viscose industry.

.An analysis gave the following results Calculated for- FoundCuH19O9.O.CS.S.CzH5= OmHaSaOm Example 3.-The procedure is as in Example2, with the exception that 70-120 parts of ethyl bromide are usedinstead of the ethyl iodide. The pro erties of the roduct resemble thoseof t e product of xample 2. Example preceding examples, with theexception that 40-100 parts of dimethyl sulphate are used instead of theinorganic acid esters named therein.

Ewampl'e 5.-The procedure is as in the i I preceding examples, with theexception that 100-1-50 parts of methyl iodide are used in 4.-Theprocedure is as in the place of the alkylating agents named therein.

The properties of the final product resemble those of the amples. y

Inthe foregoing examples, there may be used as parent material a viscosewhich has been purified, for example by precipitating I with'commonsalt, washing with a solution products of the preceding ex- 1 be used aviscose which differs claims permits, thate and viscose lncludecellulose-Xanhas been removed, neutralization 'of the viscose is notnecessary. 7

In all the foregoing examples, there may from the viscose used inExample 1 in the extent to which the soda-cellulose is pressed, and in vthe proportion of. carbon disulphideused. Thus, for instance, thesoda-cellulose may be pressed until its weight is reduced to 200 parts,and it may be treated with only 20- 25 arts of carbon disulphide.

herever the context of the following the terms cellulose-xanthic acids,and the term substanti ally neutral includes the absolutely neutral, the

faintly acid and the faintly alkaline condi-I tions. I I claim:

1. Process for making new cellulose compounds which process comprisesacting on a cellulose-xanthate with an ester of an inorganic acid undersubstantially neutral condition. f

2. Process for making new cellulose compounds which process comprisesacting on a' cellulose-xanthate with an ester of an in,-

organic acid under faintly alkaline condition. p

. 3. Process for making new cellulose compounds which process comprisesacting on a cellulose-xanthate with an ester of an inorganic acid in theabsence of substantial amounts of alkali. V I

4:. Process for making new cellulose compounds which process comprisesacting on viscose with an ester of an inorganic acid under substantiallyneutral condition.

5. Process forv making. new cellulose compounds which process comprisesacting on viscose with an ester of an inorganic acid under faintlyalkaline condition.

6. Process for making new cellulose compounds which process comprisesacting on viscose with an ester of an inorganic acid in. the absence ofsubstantial amounts of alkali. v

7. Process for making new cellulose compounds which process comprisesacting'on a cellulose-xanthate with an alkyl ester under substantiallyneutral condition.

8. Process for making new cellulose compounds which process comprisesacting on a cellulose-xanthate with an alkyl'ester under faintlyalkaline condition.

9. Process for making new cellulose compounds which process comprisesacting on a cellulose xanthate with an alkyl ester in the absence ofsubstantial amounts of alkali.

10. Process for making new cellulose compounds which process comprisesacting on viscose with an alkyl ester under substantially neutralcondition.

- 11: pounds which process comprises acting on viscose-with an alkylester under faintly alkaline condition.

12. Process for'making new cellulose compounds which process comprisesacting on viscose with an alkyl ester in the absence of substantialamounts of alkali.

13. As new products esters of cellulos xan'thic acids.

14.. As new products alkyl esters of cellulose xanthic acids. I

15. As new products ethyl esters of cellulose xanthic' acids.

In testimony whereof I afiix' my signature.

LEON LILIENFELD.

Process for making new cellulose com-

